Unipolar p-type single-walled carbon nanotube field-effect transistors using TTF–TCNQ asthe contact material

Abstract

We demonstrate herein that organic metal tetrathiafulvalene–tetracyanoquinodimethane(TTF–TCNQ) can serve as an ideal material for source and drain electrodesto build unipolar p-type single-walled carbon nanotube (SWNTs) field-effecttransistors (FETs). SWNTs were synthesized by the chemical vapor deposition(CVD) method on silicon wafer and then TTF–TCNQ was deposited by thermalevaporation through a shadow mask to form the source and drain contacts. AnSiO2 layer served as the gate dielectric and Si was used as the backgate. Transfer characteristicsshow that these TTF–TCNQ contacted devices are Schottky barrier transistors just likeconventional metal contacted SWNT-FETs. The most interesting characteristic of theseSWNT transistors is that all devices demonstrate the unipolar p-type transport behavior.This behavior originates from the unique crystal structure and physical properties ofTTF–TCNQ and this device may have potential applications in carbon nanotubeelectronics.